Flexible piston for internalcombustion engines



May 15, 1945. P. s. WEBSTER FLEXIBLE PISTON F O R INTERNAL-COMBUSTION ENGINES '2 Sheets-Sheet 1 Filed July 15, 1943 J l i a 4 5 May -15, 1945. P. s. WEBSTER FLEXIBLE PISTOifFOR INTERNAL-*COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed July 15', 1943 llllllllllllllllll |lm 0 l P I EXPANSION COMPRESSION cqMeusr/o/v ATMaJ/WERZ- LIA/E pfz 'lip 5. Web:

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Patented a, 15, 1945 FLEXIBLE PISTON FOR INTERNAL- OOMBUSTION ENGINES Philip S. Webster, Muskegon, Mich.

Application July 15,1943, Serial No. 494,758

1 Claim. (01. 123-18) The present invention relates to flexible pistons for internal combustion engines and more particularly to an improvement over or modification of the flexible piston illustrated and described in my co-pending application for Letters Patent of the United States of America, Serial No. 435,272,

flled March 19, 1942, to issue July 6, 1943, as Patent No. 2,323,742.

The primary objects of the instant invention are to provide a piston for an internal combus tion engine of the general character above indicated whereby detonation is controlled; to provide'a piston having an auxiliary head which compresses the exhaust gases of the previous cycle into the combustion chamber, causing added turbulence and resulting in a more uniform burning of the compressed mixture of fuel and air; to provide such a piston whose auxiliary head is secured to but flexibly spaced from its lower portion permitting free absorption of excess combustion pressure during periods of ignition and burning after which it returns to normal position and before the exhaust valve releases the ex-v panded gas; to provide such a piston whose auxiliary h ad retains the exhaust gases during the succeeding intake and compression strokes, thereby acting as a shock absorber and preventing excessive detonation; to provide such a pis ton, the flexible movement of whose auxiliaryhe'ad may be varied and initially determined to suit any particular available fuel; to provide such a piston whose auxiliary head is provided with rings, and is concentric with the cylinder walls at all times, thereby providing for uniform heat transfer through its rings without scufflng or lar to Figure 3 but showing'the auxiliary head of the piston in depressed position;

Figures 5. 6 and 7 show the combustion cycle of the flexible piston within its cylinder; and

Figure 8 diagrammatically illustrates how detonation is prevented andhow improved performance results from the use of the flexible piston of this invention, v

flexible pis- Referring then to the drawings wherein like parts of the structure shown are each designated by the same numerals in the several views, the vertically flexible or axially expansible-contractible piston there shown generally is preferably of cast aluminum alloy and comprises an upper auxiliary portion or combustion head ill, a lower portion ll having oppositely disposed wrist pin receiving apertures l2, a central connecting member l3 having oppositely disposed wrist pin slots H for securing the upper auxiliary portion I0 to the power portion II by means of the wrist pin' I00, and a bellows type expansion spring It interposed between the upper auxiliary portion In of the piston and the lower portion I I thereof.

The upper auxiliary portion lot the piston is provided with a centrally disposed bore i6, downwardly tapered at its upper end and likewise preferably having a tapered steel annular insert l1 and the central connecting member I3 is further provided with a centrally disposed bore l8 in alignment with the bore ii of the upper auxiliary portion It. A bolt I!) provided with a tapered head 20 and with a screw threaded shank 2| flexibly secures the upper auxiliary portion 10- of the piston with the central connecting member i3 by means of the nut 22.

The upper auxiliary portion ill of the piston is provided with conventional compression and oil ring grooves 22, 23, respectively, and with a dependingsleeve 24, preferably of steel, within itsinternal bore. The central connecting member I3 is preferably provided with a plurality of piston ring grooves 25 within which are seated oil rings 26 engaging the inner surface of the depending sleeve 24 and the lower portion of the piston is provided with a compressing ring groove 50.

In securing the several parts of the piston in their assembled relation, the bellows type expansible spring I 5 is first slid upwardly around the depending sleeve 24 and the central connecting member I3 is then slid upwardly through the bore of the lower portion H of the piston to compress the bellows type spring after which the bolt i5 is inserted through the bores l6, l8 and the nut 22 turned on the shank 2| to secure the 11 per auxiliary portion ill of the piston and the central connecting member l3 whereupon the wrist pin III is inserted through the apertures l2 and slots ll the upper auxiliary portion it of the piston to axially space itself from the lower portion I i thereof.

Combustion of the atomized fuel within the. cylinder 28 above the auxiliary upper portion of a the piston '10 by means of the spark plug 28 causes the head to travel axially from its position shown in Figure 5 compressing the bellows ype spring 15 as shown in Figure 6, whereupon the central connecting member [3 is depressed to its position shown in Figure 7, at which time the pressure during periods of ignition and burning after which it returns to normal position,. and before the exhaust valve releases the expanded gas, that the auxiliary upper portion or the piston provided than are pr'owlded with conventional type pistons using standard grades of fuel.

Detonation is prevented by the added turbulence of the exhaust gases in the chamber mixing with the combustible mixture of fuel and air as the gas pressure increases to displace the upper auxiliary portion of the piston 10 relative to the- Thus, an engine having an lower portion 11. eflective compression ratio of ten to one on the exhaust and intake stroke will have the detonation and power characteristicsof an engine having a five to one compression ratio, all as indicated in Figure 8 wherein the ordinate. indicates pressure, the abcissa indicates volume, the crosshatching indicating an engine with standard pistons and the dotted lines indicating an engine having flexible pistons 01 the instant invention.

It will thus be seen that the flexible piston herein shownand described is well adapted to control detonation, that the auxiliary upper portion'which compresses the exhaust gases of the retains the exhaust gases during the succeeding intake and compression strokes thereby acting as a shock absorber and preventing excessive detona tion, that the flexible movement between the sew eral portions of the piston may be varied and initially determined to suit any particular available iuel, that the auxiliary upper portion of the piston is provided with rings and said portion is concentric with the cylinder walls at all times thereby providing for uniform heat transfer through its rings without scliflihg or blow-by, and that the flexible piston herein shown and de scribed is reasonably light in weight, highly em previous cycle into the combustion chamber causes cured to but flexibly spaced from its lower portion permitting free absorption of excess combustion cient in use and reasonably economical in manuiacture.

While but one specific embodiment of the invention has been herein shown and described, it will be understood that certain details of the construction shown may altered or omitted withoutde rting from the spirit of the invention as the same is defined by ,the following claim.

I claim:

A, piston for an internal combustion engine having a hollow head portion and a lower portion inspaced relation thereto, the inner wall of the hollow head portion having a close fitting depending sleeve, a connecting member limitedly slidably disposed relative to the lower portion secured to the upper portion thereof and provided with ring grooves havingsealing rings therein, and a bellows type expansion spring interposed in the space between the upper and lower portions of the piston.

I V PHILIP S. 

